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Speed up LZSA2 compression

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Emmanuel Marty 2019-10-08 20:26:21 +02:00 committed by GitHub
parent 44df8f3d2d
commit 03f841d04f
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GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 42 additions and 37 deletions
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15
src/shrink_block_v2.c
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@ -295,13 +295,14 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
int nMatchOffsetCost = (nMatchOffset == nRepOffset) ? 0 : nNoRepmatchOffsetCost;
int nRepCodingChoiceCost = nPrevCost + 8 /* token */ /* the actual cost of the literals themselves accumulates up the chain */ + nMatchLenCost;
int nCodingChoiceCost = nRepCodingChoiceCost + nMatchOffsetCost;
int exists = 0;
if (!nFavorRatio && !arrival[(i << MATCHES_PER_OFFSET_SHIFT) + j].num_literals)
nCodingChoiceCost += MODESWITCH_PENALTY;
if (pDestSlots[NMATCHES_PER_OFFSET - 1].from_slot == 0 || nRepCodingChoiceCost <= pDestSlots[NMATCHES_PER_OFFSET - 1].cost) {
if (pDestSlots[NMATCHES_PER_OFFSET - 1].from_slot == 0 || nCodingChoiceCost <= pDestSlots[NMATCHES_PER_OFFSET - 1].cost) {
int exists = 0;
for (n = 0;
n < NMATCHES_PER_OFFSET && pDestSlots[n].from_slot && pDestSlots[n].cost <= nCodingChoiceCost;
n++) {
@ -311,7 +312,8 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
}
for (n = 0; !exists && n < NMATCHES_PER_OFFSET; n++) {
if (!exists) {
for (n = 0; n < NMATCHES_PER_OFFSET; n++) {
lzsa_arrival *pDestArrival = &pDestSlots[n];
if (pDestArrival->from_slot == 0 ||
@ -334,15 +336,16 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
}
}
}
/* If this coding choice doesn't rep-match, see if we still get a match by using the current repmatch offset for this arrival. This can occur (and not have the
* matchfinder offer the offset in the first place, or have too many choices with the same cost to retain the repmatchable offset) when compressing regions
* of identical bytes, for instance. Checking for this provides a big compression win on some files. */
if (nMaxRepLen[j] >= k) {
/* A match is possible at the rep offset; insert the extra coding choice. */
int exists = 0;
exists = 0;
/* A match is possible at the rep offset; insert the extra coding choice. */
for (n = 0;
n < NMATCHES_PER_OFFSET && pDestSlots[n].from_slot && pDestSlots[n].cost <= nRepCodingChoiceCost;
@ -353,7 +356,8 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
}
for (n = 0; !exists && n < NMATCHES_PER_OFFSET; n++) {
if (!exists) {
for (n = 0; n < NMATCHES_PER_OFFSET; n++) {
lzsa_arrival *pDestArrival = &pDestSlots[n];
if (pDestArrival->from_slot == 0 ||
@ -381,6 +385,7 @@ static void lzsa_optimize_forward_v2(lzsa_compressor *pCompressor, const unsigne
}
}
}
}
lzsa_arrival *end_arrival = &arrival[(i << MATCHES_PER_OFFSET_SHIFT) + 0];
pCompressor->best_match[i].length = 0;